<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>入门案例</title>
</head>
<body>
    <div id="div">qwer</div>
</body>
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    <script src="js/jquery-3.3.1.min.js"></script>
    <script>

    </script>
    <!--<script>
        let jsdiv=document.getElementById("div");
        alert(jsdiv);
        alert(jsdiv.innerHTML);
    </script>-->
</html>